Power supply apparatus

Abstract

There are provided a first arm circuit and a second arm circuit (1020, 1021) each including an upper arm and a lower arm; a series resonant circuit including a first inductor (Lr1) and a capacitor (Cr1), the first inductor having one end thereof connected with a first end of primary winding of a transformer (Tr), the capacitor being connected with the other end of the first inductor; a second inductor (Lr2) having one end thereof connected with a connection point connecting the upper arm with the lower arm in the second arm circuit; and a control circuit (10) controlling drive of the first and the second arm circuits. A connection point connecting the upper arm with the lower arm in the first arm circuit is connected with a second end of the primary winding of the transformer. A connection point connecting the first inductor with the capacitor is connected with the other end of the second inductor.

1 . A power supply apparatus comprising:
 a first arm circuit that includes a first switching element and a second switching element, the first and second switching elements being connected in series between positive and negative terminals of a direct-current power supply, the first switching element constituting an upper arm, the second switching element constituting a lower arm;   a second arm circuit that includes a third switching element and a fourth switching element, the third and fourth switching elements being connected in series between the positive and negative terminals of the direct-current power supply, the third switching element constituting an upper arm, the fourth switching element constituting a lower arm;   a transformer that includes primary winding, and secondary winding with which an output circuit outputting a direct current is connected;   a series resonant circuit that includes a first inductor and a capacitor, the first inductor having one end thereof connected with a first end of the primary winding, the capacitor being connected with the other end of the first inductor;   a second inductor that has one end thereof connected with a connection point connecting the third switching element with the fourth switching element in series; and   a control circuit that controls drive of the first arm circuit and the second arm circuit,   wherein a connection point connecting the first switching element with the second switching element in series is connected with a second end of the primary winding of the transformer, and   a connection point connecting the first inductor with the capacitor is connected with the other end of the second inductor.   
     
     
         2 . The power supply apparatus according to  claim 1 ,
 wherein the control circuit drives the first arm circuit and the second arm circuit in phase with each other.   
     
     
         3 . The power supply apparatus according to  claim 1 ,
 wherein the control circuit switches the second arm circuit between a stopped state and an operating state at a predetermined level of power output from the output circuit.   
     
     
         4 . The power supply apparatus according to  claim 1 ,
 wherein the control circuit switches the second arm circuit from a stopped state to an operating state by gradually varying duty of a PWM signal for driving the second arm circuit.   
     
     
         5 . The power supply apparatus according to  claim 1 ,
 wherein the control circuit drives the first arm circuit and the second arm circuit in opposite phase to each other.   
     
     
         6 . A power supply apparatus comprising:
 a first arm circuit that includes a first switching element and a second switching element, the first and second switching elements being connected in series between positive and negative terminals of a direct-current power supply, the first switching element constituting an upper arm, the second switching element constituting a lower arm;   a second arm circuit that includes a third switching element and a fourth switching element, the third and fourth switching elements being connected in series between the positive and negative terminals of the direct-current power supply, the third switching element constituting an upper arm, the fourth switching element constituting a lower arm;   a transformer that includes primary winding, and secondary winding with which an output circuit outputting a direct current is connected;   a series resonant circuit that includes a capacitor and a first inductor, the capacitor having one end thereof connected with a first end of the primary winding, the first inductor having one end thereof connected with a second end of the primary winding;   a second inductor that has one end thereof connected with a connection point connecting the third switching element with the fourth switching element in series; and   a control circuit that controls drive of the first arm circuit and the second arm circuit,   wherein a connection point connecting the first switching element with the second switching element in series is connected with the other end of the first inductor, and   the other end of the second inductor is connected with a connection point connecting the capacitor with the first end of the primary winding.   
     
     
         7 . The power supply apparatus according to  claim 6 ,
 wherein the control circuit drives the first arm circuit and the second arm circuit in phase with each other.   
     
     
         8 . The power supply apparatus according to  claim 6 ,
 wherein the control circuit switches the second arm circuit between a stopped state and an operating state at a predetermined voltage of direct-current power supply output from the output circuit.   
     
     
         9 . The power supply apparatus according to  claim 6 ,
 wherein the control circuit switches the second arm circuit from a stopped state to an operating state by gradually varying duty of a PWM signal for driving the second arm circuit.   
     
     
         10 . The power supply apparatus according to  claim 6 ,
 wherein the control circuit drives the first arm circuit and the second arm circuit in opposite phase to each other.